[ros-users] using ROS with a new 7-DOF arm hardware

Patrick Beeson beeson.p at gmail.com
Tue Jun 14 00:24:46 UTC 2011

I'd be more the glad to help alpha test and work through this stuff
prior to release.  Feel free to send along the current documentation.

I believe my intern created a reasonable URDF before he left for a
week of personal time.  I'll try to track that down.  I'll also start
writing my own  joint_trajectory_action if needed.  One thing I was
confused about was joint_tractory_action.  That package exists is the
pr2_controllers stack.  Can't I simply use than and then have it
subscribe to my controller for status and publish controller commands?
 Why do I need to write my own if one exists?  Or did you mean that
I'll need to write my own node to handle the joint_tracjectory
messages from the joint_trajectory_action node?

On Mon, Jun 13, 2011 at 1:59 PM, Gil Jones <gjones at willowgarage.com> wrote:
> Hi Patrick,
> We are currently actively (as in right this second) developing a tool
> chain that assists users in configuring and building applications for
> arm navigation on novel platforms.  We're aiming to have all of this
> working reliably and in a documented fashion in time for the release
> of e-turtle later this summer.  In the meantime, if you are interested
> in being an alpha tester of this functionality I can send you a
> rosinstall file and tell you a bit about how the tool chain works -
> this should definitely be the fastest way to go from a urdf to solving
> kinematics and generating collision-free trajectories for your arm
> using our software.  This is with the usual caveats that things aren't
> quite ready for prime-time.
> To use this new functionality you'll need a urdf and your own
> joint_trajectory_action, but all the intermediate configuration and
> launch file generation should be done for you.  This also doesn't help
> configure any of our manipulation stacks - those will not be released
> at 1.0 in e-turtle.
> All the documentation, etc will be cleaned up in conjunction with the
> e-turtle release, and now that we're taking the plunge towards a 1.0
> release of major parts of the system things should be substantially
> more stable as of e-turtle.
> -Gil
> --
> E. Gil Jones (gjones at willowgarage.com)
> Research Engineer
> Willow Garage, Inc.
> 68 Willow Road
> Menlo Park, CA 94025
> 650.475.9772
> On Mon, Jun 13, 2011 at 11:36 AM, Patrick Beeson <beeson.p at gmail.com> wrote:
>> I'm attempting to try and utilize novel, custom-made 7-DOF modular arm
>> hardware with ROS, and I'd like any help people are willing to provide
>> in starting from scratch with getting a new arm working in ROS.  I
>> have lots of familiarity with ROS, writing ROS drivers for perception
>> and navigation hardware, but, I'm not a manipulation or kinematics
>> expert, and I'm having difficulties understanding exactly what I do
>> and do not need to implement on my end to use the move_arm high level
>> package.
>> Having previously used the navigation stack, and other such stacks,  I
>> assumed that I would need some sort of driver that would subscribe to
>> some topic that would send joint positions or velocities based on
>> higher level kinematics planning given URDF models of the joints.
>> Instead, what I found was this tutorial:
>> http://www.ros.org/wiki/arm_navigation/Tutorials/Running%20arm%20navigation%20on%20non-PR2%20arm,
>> which seems to imply the need for writing my own kinematics plugin in
>> addition to my own joint trajectory execution node.  I can certainly
>> do this given some time; however, previous emails implied a
>> generic_kinematics package in unstable that would be useful, but after
>> searching through the Subversion repository, a generic_kinematics
>> package does not exist anywhere.
>> So, I'm going to start my creating a joint_trajectory_execution node
>> that has a a joint_trajectory_action interface and does soft-realtime
>> control of my joints behind the scenes.  What I need help determining
>> is if/where any generic kinematics packages exist or if I need to
>> write my own for my arm.  If I need to write my own, more details on
>> how to get this working with the other relevant modules would be
>> useful.  If a generic package exists, where is it?  How do I feed it
>> the model of my arm?  Also (tutorial step 5) there are lots of other
>> bits and pieces lying around that need to get tied together that
>> aren't well documented.  All in all, what I need is a better tutorial
>> that gives a much more simplified explanation as to what pieces are
>> needed, how they fit together (from move_arm down to hardware
>> interface), what parameters are definitely needed and which can be
>> ignored, etc.
>> Any help on this would be appreciated.  I'm sure I could figure all of
>> this out given enough time, but these days, time is not a great luxury
>> that I have, and part of the reason I use ROS is that it has been easy
>> to create, use, swap nodes, messages, topics with relative ease.  the
>> ARM documentation however is quite lacking and the large number of
>> motion planning, kinematics, controller, and action modules are not
>> well documented as to what is deprecated, how things fit together,
>> etc.
>> Thanks in advance,
>> Patrick
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